Process of coking pitch



Patented Nov. .22, 1927.

UNITED STATES 1,650,127 PATENT OFFICE.

BAY P. PERRY, OI UPPER MONTCLAIB, NEW JERSEY, ASSIGNOR TO THE BARRETT ICOMPANY,

A CORPORATION OF NEW JERSEY.

PROCESS OF OOKING PITCH.

Application filed Apirl 5,

As distinguished from thecoking of coal and of certain grades ofcoal-tar pitch which are not or do not become thoroughly liquid in thecoking process, my invention relates to the coking of coal-tar pitch andthe like under conditions where or when the material is in such acondition that it is introduced in a liquid condition into the cokingchamber or becomes liquefied by heat in such chamber in the course ofthe coking process or before 1 .the coking operation takes place.

In most types of modern equipment for coking coal, such for example asso-called by-product coke ovens or gas retorts, it is customary tosupply the heat required for the coking process through the walls of thecoking chamber. For example, in a byproduct coke oven the heat issupplied through the side walls of the oven, the heating flues in theseside walls and the heating ases in the fiues being distributed and regu-Iated so as to produce a substantiall constant and uniform temperatureover the entire side walls of the oven. This permits thorough andsubstantially uniform coking of the entire charge of coal in the oven,the coking rogressing from the two sides toward t e median line of thecharge.

Because of the successful coking of coal in such by-product ovens, itwas expected that coal-tar pitch could be satisfactorlly coked in thesame ovens and in the same way, but in the attem ts to coke liquid orliquefiable coal-tar pitc serious difficulties have been encounteredwhich render the process unsuccessful and make the coke unsatisfactoryfor certain purposes. The pitch, upon being heated to a certain criticaltemperature, ap pears to have some of its const tuents decomposed, or atleast there is a very large evolution of gases and vapors resulting 1nsudden and rapid development of pressure, accompanied by expansion andfoaming of the li uid mass. This critical temperature depen s upon themelting point and other characteristics of the pitch and can be easilyascertained by trial.

If a mass of liquid or liquefiable pitch is heated in a by-product cokeoven in the so manner customary in coking coal, there sets up in thepitch, when it is in a liquid condition, a natural thermal circulationor convection currents by which the entire liquid mass is raised to asubstantially uniform to temperature throughout, and consequently I tionof the pitch charge 1922. Serial N0. 549,664.

when a suflicient amount of heat has been supplied to reach the criticaltemperature mentioned above, it will be noted that the entire mass atone time may be at this temperature as distinguished from the conditionsresent in coking coal. Coal being nonlique able, does not have a thermalcirculation and does not reach a uniform temperature throughout, but onthe contrary the heat penetrates slowly and the coal is coked slowly andprogressively from the two sides towards the centerwitha consequentlyless violent or sudden evolution of gases.

Ihave discovered that the unsatisfactory condition and troubles arisingin coking liquid or liquefiable pitch can-be minimized or avoided by,applying from the top or from the sides near the top suflicient heat forconverting the top portion only of the liquid pitch into coke with theaccompanying large gas evolution from that portion, while the remainderof the charge of pitch in the oven, although a considerable portion orall of it may be in liquid form, is nevertheless maintained at atemperature below that at which the heavy gas evolution takes place inchanging from pitch into coke. After this top porhas passed the criticalgas evolution stage, I continue the coking rogressively in a downwarddirect1on eit er continuously or intermittently, applying a sufiicientamount of heat for convertingonl a small portion at a time of theliquid-pitc near-the top into coke, while the balance of the chargebelow, although it may be liquid, is maintained at a temperature belowthe heavy gas evolution sta e.

The invention Wlll be-understood rom the descri tion in connection withthe drawings whic illustrate an apparatus for carrying out the process.In the drawings Fig. 1 is a vertical section of an oven.

Fig. 2 is a section along the line H of Fig 1.

ig. 3 is an end section of a modified form of oven.

In the drawings reference character 1 indicates the wall of an ovenwhich is provided with a bottom 2 and a cover 3. An outlet 4extendsthrough the cover 3, and a pair of openings are shown at 5 through whichthe material may be charged.

A series of horizontal conduits or flues 6,

7 8, 9, etc., extend through the walls of the oven. klhese flues 6, 7,etc. are connected by means of the pipes 6, 7', etc. which are furnishedwith valves 6", 7 etc. with a feed or inlet pipe 10 for hot gases or forhot products of combustion, and the other end of these conduits or fluesare connected to a common header 11, through which thehot products aredischarged.

In the modification shown in- Fig. 3 the apparatus is substantially thesame as above described except that the oven 1' is made with walls whichflare outwardly in an up either in the solid or liquid state. Assumingthat the oven is in a hot condition from a preceding coking operation,the pitch will be melted if the same is not already in a moltencondition. Heat will be supplied to the oven through the upper flues 6by opening the valve 6" whilethe remaining part of the oven is notsubjected to the increased heat. As a result of this method of heating,the pitch forming the upper'layer or upper portion of the mass will beheated to the critical temperature with a consequent evolution of gasand resulting coking of this portion. After the upper portion of thecharge of pitch has been coked, heat may be applied in a lower set offlues 7 to cause the .coking of the next layer of pitch to take lace ina similar way. By then applying heat in the lower flues, the coking willprogress downwardly toward the bottom.

It is possible to perform the coking op-' eration as above described insuch a manner that the pitch atdistances considerably below'the portionthat is being coked will not be liquefied. In this way the convectioncurrents or circulation oi pitch may be minimized, thereby furtherlimiting the danger of sudden evolution of gas froman exceedingly largemass of the pitch. When the coking is produced inthe oven, as indicatedin Fig. 3, the molten pitch is supplied through the inlet 5 and as thecokin takes place near the top, the layer of cofie formed may beremoved, thus permitting the introduction of more pitch through theinlet 5' and raising the level of the mass so that another layer at thetop may be coked without at any time fully dlscharging the oven.

The coke made in accordance with this process is substantially free fromsulfur and ash and possesses very high mechanical stren h so that thesame can be used in a foun ry cupola. The coking of the pitch from thetop downwardly appears to make the same very much stronger than theordinary methods of coking. It will be clear 1,eEso,127

that this method of coking pitch may be carried out in a vertical gasretort or' other coking chamber such as the ordinary'type of beehiveoven, the important and distinguishing feature being that the heat whichis to cause the coking of the pitch should be supplied first at or nearthe top of the pitch undersuch conditions that there would be noobjectionable thermal circulation or convection currents throughout themass. Care should be exercised regardless of the sort of oven in whichthe coking is made to take place, so that the heat would not be suppliedin sufficient quantities throughout the entiremass to bring the mass tothe temperature at which there would be a large gas evolution stage atone time. The thermal circulation incidental to the liquid condition ofthe pitch seems to be of no particular disadvantage if the pitch ismaintained below the large gas evolution coking stage. An advantage thatis obtained by coking the pitch downwardly in a by-product coke oven,for example, is that the evolved gases can be collected and the valuableby-producta coking first to the upper ortion of the mass and thenprogressively ownward through thev mass, while retaining the masslwedgeshaped with the narrower portion downwards. A

3. The process of cokin hydrocarbon pitch that is solid at normatemperatures which comprises coking an upper portion oi the mass whilemaintaining a lower por-" tion of the mass in a liquid but non-cokingcondition, any lower layer of said mass being narrower than a layerthereabove.

4. The process of coking amass of liquid hydrocarbon pitch,,"whichcomprises coking an upper portion of the. mass while maintaining a lowerportion of the massin :a liquid but non-coking condition, and addingmore pitch to theliquid non-coking rtion.

5. The process of coking a mass o liquid hydrocarbon pitch, whichcomprises coking an upper portion of the mass while maintaining a lowerportion of the mass in a 6. The process of coking liquid -hydro-' carbonpitch in an oven, which consists in coking first the upper portion ofthe mass of pitch and then coking the balance of the mass progressivelyin a downward direction by successively transmitting heat 'throu h thewalls of the oven to lower planes of t a mass.

7. The process which comprises applying heat to the upper portion of amass of hydro carbon pitch, until coking of said portion takes place,and then applyin heat to a lower portion of the pitch, sai heat beintransmitted to both said portions through the walls of the container inwhich the pitch is being coked.

8. The process of coking a liquid hydrocarbon pitch in an oven, whichconsists in coking an upper portion of the mass by means of heattransmitted through the walls of the oven without coking any portiontherebelow until the coking of such upper portion is substantiallycomplete.

9. The process of cokin in an oven a mass of hydrocarbon pitch wliquefiable by heat, which comprises supplying the heat for coking firstto the upper portion of the mass and then pro ressively downward throughthe mass, an recovering the volatile constituents driven off from thehydrocarbon pitch.

10. The process of coking in an oven a mass of hydrocarbon pitch whichis liquid or iiquefiable by heat, which comprises transmitting the heatfor coking through the walls of the oven first to the upper portion ofthe mass and then progressively downward through the mass, oven anatmosphere which will not support combustion, and recovering thevolatile constituents driven ofi from the hydrocarbon pitch.

In testimony whereof I aflix my signature.

BAY P. PERRY.

maintaining in the 'ch is liquid or

